Polyether esters

ABSTRACT

Polyether ester polymers of tetrahydrofuran and  gamma -butyrolactone or hexamethyleneoxide and  gamma -butyrolactone. The polymers are prepared by contacting the mentioned monomers in the presence a fluoride or chloride of antimony or a chloride of tin or titanium. The polymers can be used as components in the preparation of polyurethanes.

The invention relates to copolymers of tetrahydrofuran (THF) andγ-butyrolactone (γ-BL) and copolymers of hexamethylene oxide (HMO) andγ-BL, which may be described by the following formulas: ##STR1##

In Formulas I and II, n and m represent positive whole numbers; theratio of n to m may be between 100 : 1 and 1 : 100 , and the sum of nplus m may assume values between 2 and 1000.

The fundamental building blocks of the copolymers have a randomarrangement; there is reason, however, to suppose that, insofar aspossible, a γ-BL building block is followed by a THF or HMO buildingblock, as the case may be.

For the sum of n plus m, values of 4 to 250 are preferred.

Copolymers between cyclic ethers and lactones have already beenprepared. In the copolymerization of cyclic ethers with lactones,however, the number of cyclic members in the two monomers is of greatimportance; for example, although it is not difficult to copolymerizeepoxides or oxacyclobutane with β-propiolactone, δ-valerolactone orε-caprolactone by means of cationic initiators (H. Cherdron and H. Ohse,"Makromolekulare Chem." 92 (1966)), p. 213, and Y. Yamashita,"Macromolecules," Vol. 2, No. 6 (1969) p. 613), copolymers of THF andβ-propiolactone, δ-valerolactone and ε-caprolactone are much harder toobtain. For example, Cherdron and Ohse ("Makromolekulare Chem." 56, 179(1962)), by the polymerization of 4-, 6- and 7-member lactones withcationic initiators such as trifluoroacetic acid or acetyl perchloratein tetrahydrofuran as solvent, apparently obtained pure polyesters, notcopolymers. Also, as our own experiments have shown, an attempt tocopolymerize THF with pivalolactone using BF₃ -etherate as initiator hasyielded virtually pure polytetramethylene oxide.

U.S. Pat. No. 3,442,867 claims a process for the copolymerization of THFwith the 4-, 6- and 7-member lactones, β-propiolactone, o-valerolactoneand ε-caprolactone using initiators containing arsenic, but copolymersof THF or HMO with the 5-member γ-BL have not been described. The reasonfor this lies in the extremely poor copolymerization tendency of γ-BL.Homopolymers have not yet been obtained, and also the list of monomerscapable of forming copolymers with γ-BL is very short; these monomersinclude trioxane and 3,3-bis-(chloromethyl)-oxacyclobutane (BCMO) (Brit.Pat. 926,904, and K. Ito, "Makromolekulare Chem." 139, 153 (1970),respectively). Trioxane and BCMO, however, are known to be stronglyinclined to form copolymers and are capable of forming copolymers evenwith vinyl monomers under the influence of cationic initiators (Minoura,"Makromolekulare Chem." 119, 86 (1968) and Higashimura, "J. PolymerSci." A-1, 7 (1969) No. 4, 1115, respectively).

Difficulty occurs, however, even in the copolymerization of γ-BL withits ring-homologous lactones; the copolymerization parameters areunfavorable, and low transformations are achieved. Thus Tada et al., inattempts to copolymerize γ-BL with β-propiolactone, setting out from amonomer mixture containing 30 mole-% γ-BL, obtained a copolymer whichcontained only 3 mole-% γ-BL building blocks. The polymerization ratewas extremely low: 2.87% in 3 days of polymerization time (K. Tada etal., "Makromolekulare Chem." 77, 220 (1964)). The copolymerization ofγ-BL with glycolide produces similarly negatives results; althoughcopolymers with β-propiolactone were obtained with the use of antimonytrifluoride as initiator, copolymers of γ-BL and glycolide could not bemade (K. Chujo et al., "Makromolekulare Chem." 100, 262 (1967).

Although under these circumstances it was rather improbable that γ-BLwould form copolymers with THF or even with HMO, nevertheless cationiccopolymerization experiments were undertaken. The fact that no polymerwas obtained with a series of cationic initiators such as trifluoraceticacid, acetyl perchlorate, BF₃ -etherate, BF₃ -etherate plusepichlorhydrine and aluminum monoethyl dichloride, appeared to confirmthe original doubts. It was all the more amazing, therefore, that, inthe presence of antimony pentafluoride or antimony pentachloride asinitiators, random copolymers with high percentages of γ-BL buildingblocks were obtained at high transformation rates from the monomer pairsγ-BL/THF and γ-BL/HMO.

The copolymers are waxy or plastic masses or highly viscous oils,depending on the content of γ-BL building blocks. The softeningtemperatures decrease as the percentage of γ-BL building blocksincreases. If, for example, poly-HMO has a melting point of 72° C(differential thermoanalysis), the melting temperature of a copolymercontaining 24 mole-% γ-BL building blocks is 50° C and that of acopolymer containing 31 mole-% γ-BL building blocks is 38° C. Whereaspoly-HMO and poly-THF represent highly crystalline polymers, thecrystalline content diminishes as the γ-BL content increases.

The copolymers have mostly OH end groups and thus may be usedpreferentially as diol components in the preparation of polyurethane.Another possible application is in the field of elasticizing agents orpolymer plastizisers e.g., for plastics.

The THF/γ-BL copolymers show the C=O valence vibration of the γ-BLbuilding block at 1730 cm⁻¹ i the infrared spectrum, the C-O valencevibration (ester) of the γ-BL building block at 1165 cm⁻¹, and the C-Ovalence vibration (ether) of the THF building block at 1100 cm⁻¹.

The NMR spectrum of the THF/γ-BL copolymer (100 MHz measuring frequency;solvent CDCl₃ ; room temperature) shows signals which may be associatedwith the following fragments of the polyether ester chain:

    __________________________________________________________________________    d = 1.61 ppm (triplet)                                                                      OCH.sub.2CH.sub.2CH.sub.2CH.sub.2O                              d = 3.25 - 3.8 ppm (triplets)                                                               CH.sub.2OCH.sub.2 CH.sub.2CH.sub.2CH.sub.2OCH.sub.2             d = 1.87 ppm (pentet)                                                                        ##STR2##                                                       d = 2.39 ppm (triplet)                                                                       ##STR3##                                                       d = 4.08 ppm (triplet)                                                                       ##STR4##                                                       __________________________________________________________________________

Under the same conditions of measurement, the NMR spectrum of theHMO/γ-BL shows signals which may be associated with the followingfragments of the chain:

    __________________________________________________________________________    d = 1.13 - 1.73 ppm (multiplet)                                                               OCH.sub.2(CH.sub.2).sub.4CH.sub.2O                            d = 3.2 - 3.7 ppm (triplets)                                                                  CH.sub.2OCH.sub.2(CH.sub.2).sub.4CH.sub.2OCH.sub.2            d = 1.79 ppm (pentet)                                                                          ##STR5##                                                     d = 2.29 ppm (triplet)                                                                         ##STR6##                                                     d = 3.99 ppm (triplet)                                                                         ##STR7##                                                     __________________________________________________________________________

The presence of a copolymer may be deducted from the presence of signalsof the cyclic ether building block and of the lactone building block ifone considers that under the conditions of the reaction ahomopolymerization of the γ-BL can be excluded. The clear solution whichcan be obtained from the polymers also speak for the presence of acopolymer; polymer mixtures would yield turbid, cloudy solutions as aresult of incompatibility phenomena. Proof of the presence of randomcopolymers is to be found in hydrolytic decomposition testing of theproducts in a alkaline medium, which leads to the formation ofoligomers. A copolymer of HMO and γ-BL containing 24 mole-% of γ-BLbuilding blocks with a molecular weight of 4500 can in this manner byhydrolyzed to oligomers of the HMO with an average molecular weight Mn(vapor pressure osmometer) of 430. Such behavior would not bereconcilable with the presence of a polymer mixture or of a blockcopolymer.

The fluorides and chlorides of trivalent and especially pwentavalentantimony serve as cationic initiators to start the copolymerization, asdo the chlorides of tetravalent tin and titanium. Antimony pentafluorideis an especially preferred initiator. Other chlorides of tin andantimony can be used.

The initiators are used in amounts of between 0.1% and 10%, preferably0.5% and 5%, of the weight of the monomer mixture. To increase the speedof copolymerization it is advantageous to add to the batches smallamounts of epichlorhydrine (ECH) of the order of magnitude of theamounts of initiator. The acceleration that can be achieved thereby isespecially apparent in the rate of copolymerizaton of the HMO/γ-BLmonomer pair which is appreciably slower than that of the THF/γ-BLcombination.

The copolymerization is preferably performed in the absence of solvents;it is also possible, however, to polymerize in the presence of largelywater-free organic solvents such as aromatic hydrocarbons or halogenatedaromatic or aliphatic hydrocarbons.

The polymerization temperature is between -100° C and + 150° C, thecopolymerization of the THF/γ-BL system being performed between -70° Cand +70° C, especially between 0° C and 50° C, while thecopolymerization of the HMO/γ-BL system is performed preferably between20° C and 120° C, especially between 50° C and 100° C.

The transformations achievable in the polymerization time of from a fewhours to 48 hours are amazingly high considering the poor polymerizationtendency of γ-BL, and they are between 60% and 80% by weight of themonomers used in the batches containing up to 30 mole-% γ-BL in themonomer mixture. In the case of the HMO/γ-BL system the copolymerizationpercentages in batches containing up to 30 mole-% γ-BL in the monomermixture are even higher than the percentages achievable under the samepolymerization conditions in the homopolymerization of HMO.

The proportion of the γ-BL building blocks incorporated into thecopolymer is great, considering the poor tendency of the monomer to formhomopolymers. FIG. 1 shows the mole-fraction m₁ /(m₁ + m₂) of the γ-BLbuilding blocks (γ-BL = M₁) in relation to the proportion (M₁ /(M₁ + M₂)of the monomer put into the batch, wherein the subscript 1 is for γ-BLor building blocks therefrom. and subscript 2 is for THF or HMO or thecorresponding building blocks. It is not, however, a copolymerizationdiagram since the mole fractions m₁ /(m₁ + m₂) have been determined athigh copolymerization rates. ##STR8##

SUMMARY

Thus, the invention provides polyether ester polymers of the formulas:##STR9##

    -A.sub.n' -B.sub.m' -A.sub.n" -B.sub.m" -A.sub.n'" -B.sub.m'"

wherein A is --(CH₂)₄ --O-- and B is ##STR10## and wherein the n's andthe m's in the sets n', m'; n", m"; n'", m'", . . . are zero or positivewhole numbers, alike or different; and the sum of n'+ m' + n" + m" +n'" + m'". . . is 2-1000.

Polymer (II) can be similarly and likewise represented with A being--(CH₂)₆ --O--.

The products of the invention are the ring opening additionpolymerization products of THF and γ-BL or HMO and γ-BL. The molarproportion of THF or HMO building blocks to γ-BL building blocks in thepolymers is in the range of 200:1 to 1:1, preferably 20:1 to 1:1. Themolecular weight (vapor pressure osmometer) can be in the range of 260to 180,000, preferably 500 to 50,000.

The polymers are prepared by contacting THF and γ-BL, or HMO and γ-BL inthe presence of a fluoride or chloride of antimony or a chloride of tinor titanium. The end groups of the copolymers mostly are OH-groupsformed by OH-groups of added water, which is used for purpose ofstopping polymerization by interruption of the growth of the polymerchain. The OH-group is the end group when TMF- or HMO-building blocksform the end of a polymer chain.

In minor amount carboxyl end groups are the end groups, also formed bymeans of OH of added water. The carboxyl-group is the end group whenγ-BL-building blocks form the end of a polymer chain (in which case thecarbonyl-cation ##STR11## of the lactone reacts with OH of water used tostop the polymerization).

As thus polymeric diols and in minor amount polymericα,ω-hydroxy-carboxylic acids respectively polymeric α,ω-dicarboxylicacids are formed in case of both end groups the polymers of theinvention are useful components in preparation of polyurethanes.

EXAMPLE 1

In a polymerization vessel provided with a stirrer and a gas feed tubethere are placed, under a nitrogen atmosphere, 140 g (1.4 moles) of HMOand 51.6 g (0.6 mole) of γ-BL. Both monomers were dried over CaH₂ anddistilled. The molar ratio of HMO to γ-BL is 70:30. With stirring, 4 gof ECH and then 4 g of SbF₅ (approx. 2 wt-%) are added drop by drop atroom temperature. The mixture is heated to the polymerizationtemperature of 80° C and the stirrer is shut off. After 48 hours thepolymerization is discontinued, the stiffened mixture is dissolved inaqueous dioxane, and the polymer is precipitated in methanol. Forrefinement it is reprecipitated from THF/methanol and dried in vacuountil the weight becomes constant. 140.4 g of a virtually colorlesscopolymer is obtained with a reduced specific viscosity of 0.44 measuredin THF (0.5% solution; 25° C). The transformation amounts to 73.5% byweight.

The NMR spectrum (measuring frequency of 100 MHz; solvent; CDCl₃ roomtemperature) shows signals at d = 1:13- 1.73 ppm (multiplet), d =3.2-3.7 ppm (triplets), d = 1.79 ppm (pentet), d = 2.29 ppm (triplet)and d = 3.99 ppm (triplet), which prove the presence of HMO and γ-BLbuilding blocks. From the intensity of the CH₂ signal of the γ-BLbuilding block at d = 2.29 ppm and the sum of the intensities of the CH₂signals at d = 1.13-1.73 ppm and d = 1.79 ppm of the HMO and γ-BLbuilding block, respectively, the percentage of the γ-BL building blocksin the copolymer was determined by ratio and proportion. It amounts to24 mole-%. The molecular weight, measured in the vapor pressureosmometer, amounts to 4500; the OH number is 21.

The copolymer is soluble in a number of organic solvents, such asacetone, chloroform, methylene chloride, THF, dioxan, acetic acid ethylester and benzene. It is insoluble in water, alcohols and aliphatichydrocarbons.

Differential thermoanalysis shows a strong endothermal peak at 50° C,which corresponds to the melting temperature. On the thermobalance (air;heating rate 8° C/min) the copolymer had the following weight losses: 1%at 230° C; 5% at 285° C and 10% at 324° C.

Similar results were obtained at polymerization temperatures of 65° and88° C, respectively.

EXAMPLES 2, 3 AND 4

Under the same procedure as in Example 1, HMO was copolymerized withγ-BL in a variety of proportions. The polymerization temperature was 80°C, the time 48 hours. 2% SbF₅ serves as the initiator together with 2%ECH. The results are summed up in the following table.

    ______________________________________                                                     Molar                γ-BL                                        γ-                                                                             ratio   Copol-                                                                              Transfor-                                                                            building                                    HMO   BL     HMO/    ymer  mation blocks OH                                   (g)   (g)    γ-BL                                                                            (g)   (%)**  (mole-%)                                                                             No.  M.sub.W *                       ______________________________________                                        90    8.62   90:10   68.5   69.5  12     18   6000                            80    17.2   80:20   77.9  80     17.7   32   2700                            60    34.4   60:40   30.3  32     30.8   52   1600                            ______________________________________                                         *Vapor pressure osmometer.                                                    **by weight                                                              

EXAMPLE 5

21 g (0.21 mole) of HMO and 7.8 g (0.09 mole) of γ-BL are placed under anitrogen atmosphere in a polymerization vessel equipped with stirrer andgas feed tube, and 1.15 g of SnCl₄ was added with stirring. The molarratio of HMO : γ-BL is 70 : 30 and the initiator concentration is 4% byweight.

The mixture is heated to the polymerization temperature of 80° C and letstand for 3 days at this temperature with the stirrer shut off.

The highly viscous mixture is precipitated by pouring it into aqueousmethanol and for refinement it is reprecipitated from THF/methanol.After drying, 10.7 g of a copolymer was obtained containing 22.6 mole-%γ-BL building blocks. The transformation is 37% by weight. The molecularweight is 2300 and the OH number is 40.

EXAMPLE 6

25.2 g (0.35 mole) THF and 12.8 g (0.15 mole) γ-BL are placed in apolymerization vessel under a nitrogen atmosphere and 0.8 g of ECH isadded, followed by 0.8 g of SbF₅, with stirring. The molar ratio of THFto γ-BL is 70 : 30 and the initiator concentration (SbF₅) is about 2% byweight. The stirrer is shut off and the mixture is let stand at roomtemperature for 24 hours.

The stiffened mixture is dissolved in aqueous THF and the polymer isprecipitated in methanol. For refinement it is reprecipitated fromdioxan in a methanol-water mixture. After drying, 24.1 g of a copolymerwas obtained. The transformation is 63.4%. As the basis for thecomputation of the percentage of γ-BL in the copolymer, the intensity ofthe γ-BL signal at d =2.39 ppm was related to the sum of the intensitiesof the THF and γ-BL signals at d = 1.87 ppm and d = 1.61 ppm,respectively. On this basis the percentage of γ-BL building blocks isdetermined to be 28 mole-%.

The molecular weight, determined with the vapor pressure osmometer,amounts to 5500 and the OH number is 16. Differential thermoanalysisshows a strong endothermal peak at 39° C, which is the meltingtemperature. The weight loss on the thermobalance (air; heating rate 8°C/min) amounts to 1% at 228° C; 5% at 272° C and 10% at 316° C.

EXAMPLE 7 TO 11

Under the same conditions of procedure as in Example 6, THF wascopolymerized with various amounts of γ-BL. The reaction temperature is20° C; the polymerization time is 24 h. 2% SbF₅ + 2% ECH served as theinitiator system in Examples 7, 8, and 9, and 4% SbF₅ + 4% ECH inExamples 10 and 11. The results are summarized in the following table:

    ______________________________________                                                     Molar                γ-BL.sup.1                                         ratio   Copol-                                                                              Transfor-                                                                            building                                    THF  γ-BL                                                                            THF:    ymer  mation blocks OH                                   (g)  (g)     γ-BL                                                                            (g)   (%).sup.3                                                                            (mole-%)                                                                             No.  Mn.sup.2                        ______________________________________                                        36   4.27    90:10   26.5  57     8.1    14   7000                            28.8 8.5     80:20   23.6  63     14.6   17   5500                            21.6 17.1    60:40   14.7  38     32.3   58   1500                            18.0 21.7    50:50   9.9   25     35.6   62   1350                            10.8 29.7    30:70   11.5  28     49.4   56   1200                            ______________________________________                                         .sup.1 Quantitative NMR spectroscopy as in Example 6                          .sup.2 Vapor pressure osmometer                                               .sup.3 by weight                                                         

The copolymer of Example 10 (35.6 mole-% γ-BL building blocks) issemisolid; the copolymer of Example 11 (49.4 mole-% γ-BL buildingblocks) is a highly viscous oil.

EXAMPLE 12

25.2 g (0.35 mole) THF and 12.8 g (0.15 mole) γ-BL are placed in apolymerization vessel under a nitrogen atmosphere and 1.5 g of SbCl₅ isadded with stirring. The molar ratio of THF to γ-BL is 70 : 30 and theinitiator concentration is about 4 wt-%. The mixture is heated to thepolymerization temperature of 35° C and the stirrer is shut off. After24 hours the polymerization is interrupted and the viscous mixture ispoured into methanol to precipitae the copolymer. For refinement it wasreprecipitated from dioxan into a mixture of methanol and water.

After drying, 13.4 g of a copolymer containing 21 mole-% γ-BL buildingblocks was obtained. The transformation is 35% by weight. The molecularweight of the copolymer amounts to 2400.

In Examples 1-4 , and 6-11, wherein the system is HMO or THF and SbF₅,SbF₃ can be substituted for SbF₅, with comparable results, though theresults are better with SbF₅.

In Example 5, wherein the system is HMO and SnCl₄, THF can besubstituted for HMO, with comparable results. Also in that example, foreither HMO or THF, TiCl₄ can be used in place of SnCl₄, with comparableresults.

In Example 12, wherein the system is THF and SbCl₅, HMO can besubstituted for THF with comparable results. Also for either THF or HMO,SbCL₃ can be substituted for SbCl₅ with comparable results, though theresults are better with SbCl₅.

Other chlorides of tin or titanium can be used in place of SnCl₄ andTiCl₄, respectively.

What is claimed is:
 1. Process for the preparation of a polymer which isthe addition polymerization product of tetrahydrofuran andγ-butyrolacetone (I), or hexamethyleneoxide and Γ-butyrolactone (II),comprising contacting tetrahydrofuran and γ-butyrolactone for (I), orhexamethyleneoxide and γ-butyrolactone (II), in the presence of aninitiator, said initiator being a fluoride or chloride of antimony or achloride of tin or titanium, in an amount sufficient to initiate theaddition polymerization, and conducting said contacting at a temperatureand for a time sufficient for the addition polymerization.
 2. Processaccording to claim 1, wherein the addition polymerization product is oftetrahydrofuran and γ-butyrolactone.
 3. Process according to claim 1,wherein the addition polymerization product is of hexamethyleneoxide andγ-butyrolactone.
 4. Process according to claim 1, the temperature being-100° C to 150° C.
 5. Process according to claim 2, the temperaturebeing -70° C to 70° C.
 6. Process according to claim 3, the temperaturebeing 20° C to 120° C.
 7. Process according to claim 1, said initiatorbeing at least one of SbCl₅, SbF₅, SbCl₃, SbF₃, SnCl₄, and TiCl₄. 8.Process according to claim 7, the initiator being present in amount of0.1 - 10 wt.% with reference to the weight of the monomers.
 9. Processaccording to claim 8, and conducting said contacting in the presence ofepichlorohydrin in an amount sufficient to accelerate the reaction. 10.Process according to claim 2, said initiator being at least one ofSbCl₅, SbF₅, SbCl₃, SbF_(3l) , SnCl.sub. 4, and TiCl₄.
 11. Processaccording to claim 3, said initiator being at least one of SbCl₅, SbF₅,SbCl₃, SbF₃, Sn Cl₄ and TiCl₄.
 12. Process according to claim 10,wherein the initiator is SbF₅ or SbCl₅.
 13. Process according to claim11, wherein the initiator is SbF₅ or SbCl₅.
 14. Product produced by theprocess of claim
 2. 15. Product produced by the process of claim
 3. 16.Process according to claim 3, and conducting said contacting in thepresence of epichlorohydrin in an amount sufficient to accelerate thereaction.
 17. Process according to claim 1, wherein the mole ratio oftetrahydrofuran and γ-butyrolactone, or hexamethyleneoxide andγ-butyrolactone is such that the corresponding mole ratio in the polymeris in the range of 200:1 to 1:1.
 18. Process according to claim 4,wherein the mole ratio of tetrahydrofuran and γ-butyrolactone, orhexamethyleneoxide and γ-butyrolactone is such that the correspondingmole ratio in the polymer is in the range of 200:1 to 1:1.